Zerotools

Zerotools are a set of tools to aid keeping
virtual disks clean by filling binary zero to
those regions which are no longer in "use". This
is done on-the-fly or manually, depending on which
tool suits the needs best. The tools do not
compete with other programs that rewrite removed
files in order to make their restoration close to
impossible. Zerotools are mostly useful for people
who compress or archive virtual machines
constantly. The tools are run inside the virtualized Linux system and are distribution-agnostic.

Recent releases

Release Notes: This is a "brown paper bag" release which fixes a
long-standing misfeature of zero writes not
hitting underlying storage devices. It also
includes other performance enhancements, which
should lead to better compression of VM disks.